back in black

iTrader: (6)

hello. i have a 94 s10 with a lq9, stock heads, vindicator cam and headers.

i have a mighty demon 750 carb.

my setting as of now are, 50cc pump in front, stock squirters front and rear, stock cams, and 79 92 jetting.

it seems to run good at part throttle, and pulls really hard at full throttle but has a bad stumble when stopped full throttle from lower rpms. anything below 2700 and it bogs, below 2500 and it tries to die.

i figured i was rich at part throttle so i installed a 3.5 power valve as its all i could find. i havent driven it yet since that.

what can you suggest for fixing my problem? more aggressive secondary cam? larger squirter?

Shawn MacAnanny

iTrader: (12)

Jetting is way too rich imo. i would try something like 75/83.

What size cam are you running that you need a 3.5PV?

The larger squirter and different cams will help with the stumble also adjusting the arm on the accel pump will so that it's a later or earlier shot.

It probably wants to die down low because its running so rich. How far out are you 4 conner idle screws? Mine are 3/4 turn. Does your carb have Idle EZ?

prochargedchevyi

iTrader: (9)

Your post brings back terrible memories of my BG days. I've been working with carbs my entire life. In fact, until I started messing with LS motors, was the first time I've tried in fuel injection. In my experience, BG carbs are hit or miss, at best. This is not hearsay - these are my accounts.

I've had everything from metal shards in the fuel bowls to hair-fractures in the venturis. For a long time, I was partial to BG since I used to lived so close to their manufacturing facility. But after countless projects, I really lost faith in their quality control. Ever since 02' I've been using AED (modified Holleys) and I'll NEVER go back. Take it out of the box, bolt it on, go drive - that's how it should be.

First off, their reps will tell you that a Mighty Demon is way too aggressive for your application - which is why you're running into problems. The MD lines are reserved for high compression/high cammed motors. That's not what their brochure says, but that's the reality. I'm willing to bet that when you initially got the carb, it was eye-watering rich. Am I right? What's happening is that you're getting a lean stumble off-idle which MDs are notorious for.

Listen, if you're going to keep the carb, you might as well invest in a wideband gauge. That's the only way to get these carbs tuned correctly. Even then, it may not run the way you want it to. I literally picked up .7 tenths just from switching to and AED carb with STOCK JETS!!!! I did nothing other than switch the gasket. I've been sold on AED ever since.

In BG's defense, their carbs do have their place. I'm not trying to bash their products. You'll find many bracket and EZ Street guys running 8's and 9's with them. Unfortunately, their quality is so erradict that they've lost A LOT of customers. By all means, give it a chance. There are many tutorials on how to tune BG carbs. But honestly, unless you're looking for that 1 or 2 MPH, why should you have to go through the trouble?

Vince

Shawn MacAnanny

iTrader: (12)

Yeah you should definately take it apart and look it over. Mine had the primary and secondary metering blocks switched.

toxic99

Along with everyone else has suggested, it may be as simple as a squirter change. Have someone stay outside of car and watch exhaust, more specifically, watch for black smoke. Recreate the same situation. If it blows black smoke, decrease your squirter sizes front and back until bog is gone. If no smoke, increase squirter until stumble is gone. If niether work, check to make sure fuel isnt dripping at idle, if so, floats are too high. Truth is, it could be alot of things. But these are the most basic ones and usualy are the problem.

forcd ind

iTrader: (7)

i run a BG blowthru on my procharged LS, rem the metal shavings and used JB Weld on the leaky jet plate plugs, then dialed it in-i had to use green pump cams, #1 position, and had a light stumble that was taken care of by using a PV closer to the idle vacume(along with a/b's, jets, etc) it runs perfect now, idle to 6800, 12 lbs boost
it was free, so thats why im using it, lol